Typesafe `new Array().fill()`

[thetarnav]

new Array() returns any[], so filling it with given value doesn't narrow the array type. Maybe this could be improved here.

https://www.typescriptlang.org/play?#code/MYewdgzgLgBAhgJwTAvDMBTA7jAgkuATwAoBGABgEoA6AMwEsAbR4qgWACgB6LmPmAHoB+IA

[ArthurKa]

Array.from({ length: 10 }, () => 0).

[qb20nh]

interface Array<T> {
    fill<T2 extends T>(value: T2): Array<T2>;
}

Or do specify explicit type new Array<number>(10).fill(0)

[ArthurKa]

interface Array<T> {
    fill<T2 extends T>(value: T2, start?: number, end?: number): Array<T2>;
}

const arr = new Array(10).fill(0, 8);
[...arr].forEach(e => e.toFixed(2));